Steel vessel and method of producing same



March 14, 1933. F. GORSCHLUETER ET AL 1,900,938

STEEL VESSEL AND METHOD OF PRODUCING SAME Filed June 3, 1929 Q Patented Mar. 14, 1933 UNITED s'ra'ras FRITZ GOBSCHLUE'IEB ERNST POHL, Q1 BORSIGWEBK, GERMANY, ASSIGNORS TO BOBSIGWERK. AKTIENGESELLSCHAFT, F BOBSIGWEBK, GEBIANY, A CORN v 'IION OI GERMANY STEEL VESSEL AN D METHOD PRODUCING BAKE Application filed runes, 1929, Serial Io.

This invention relates to tanks or vessels which are adapted to contain fluids and which are subjected in use to high pressures and high temperatures.

6 For approximately the past ten years, the development of the industrial and chemicalarts has been largely centered around the application oftemperatures and pressures extremely hi h 'n comparison to those pre- 10 viously use and one of the greatest problems incident to this progressive step has been the production of apparatus capable of withstanding the new high temperatures and pressures.

' The problem was found to be particularly acute in the manufacture of tanks, vessels'or containers adapted to withstand the abnormal pressure and tem erature conditlons, for the material former y used for that purose, ordinary low carbon steel, was found to e lacking in a number of respects. ,7 p It was first discovered that an unusually on steel occurred when that substance was elevated to high temperatures. Ex riment has shown a decrease of approximate y 33 in the yield point between 'the'temperatures of 300 C. and 500 C. alone and it was therefore necessary to build tanks capable of with-- 80 standingthese temperatures, of great wall thickness in order to obtain the necessary factor of safety.

This practice occasioned not only a large loss in amount of material used but presented new problems in the manufacture of tanks steel having approximately 3% to 5% nickel.

Such a steel was found to havea relatively high ield point between temperatures of 300 to 500 C. and a decrease in wall thickness was hence permissible in the use of this alloy over the low carbon steel. How-.

ever, it was found impossible to weld the nickel steel by means of the hammer weld great decrease in the yield. point of low carp provision 0 888,182, and in. Germany larch-a8, i987.

process and this alloy could therefore not be used in the manufacture of welded tanks. Also, the costof the nickel was so great that tanks'made of then-ickel steel were more expensive to manufacture than tanks made of carbon steel despite the decrease in wall thick- Another great disadvantage incident to the use of lowcarbon steel forboiler plate is its inclinationfor a ing. Aging is the property of a steel to get rittle a long time after the steel has been worked cold and the length of this intervening period is considerably reduced when the steel has been heated to temperatures even as low as 200C. Many boil- 5 er defects noted in the past twenty years have been traced back to this property of the low carbon steel and it is therefore of great im- 7 portance to the industry to have a material which has no or practically no inclination to 7 age.

' t is an object of the present invention to rovide a material for the buildin of tanks and the like having a high yiel point at, high temperatures, little or no inclinationfoi' 7 aging, andwhich may be worked and welded as readily as any good weldable ingot iron.

Another purpose of the invention is the tanks and the like capable of withstanding abnormally high ressur'es and go without having excessive wall t ickness.

Still another object of the invention is the rovision of similar tanks and the like having ittle or no inclination for aging.

These and other objects of the invention will become more readily apparent upon a study of the following description when read in connection with the accompanying drawing which forms a. part thereof.

-In the drawing? Fig. 1 is a longitudinal cross section througha vessel formed according to our invention.

Fig. 2 is a transverse section of the same.

The present invention is based upon the D5 discovery that certain ,molybdenum alloy steels have an unexpectedly high yield point at high temperature and that such alloys may be readily hammer welded orotherwise worked by methods heretofore employed Per cent Carbon .05 to .25 Molybdenum .2 to .5 Aluminum .05 to .2

=difl'er materiall aret having a yield poiipt The manufacture of this alloy does not from the processes now used in the pro notion of other steels. -The molybdenum is added in they furnace either as ferromolybdenum or as calciummolybdat. It may also be added in the ladle but only in the form of ferromolybdenum. The aluminum is added in the ladleand in the case of electric furnaces, it may be added in the oven after .the reduction is completed.

The carbon content is necessarily held low in order that the alloy may readily be worked and easily welded when heated with water gas or coke. The molybdenum serves to impart high mechanical resistance to thealloy at high temperatures and the aluminum acts to prevent or reduce aging to a minimum. After the allo has been made, the metal is cast androlle into sheets from which plates of appropriate size are out. These plates b means of a coke fire or by use of a suitable gas, preferably water gas, and are hammer-welded together to form vessels of the desired shape and size. The metal may also be cast into plates of such shapes that. they ma be used directly in the fabrication of suc vessels.

The drawing shows a vessel formed according to the invention. All the parts of this vessel are made preferably from the alloy disclosed above, and all the seams are heated by water gas and hammer welded. The plates 1 are first bent to semi-c lindrical shape and are welded to form cylindrical sections alon the lines 4. These sections are annealed an are next welded together along the lines 6. The ends 2 are pressed to shape and are welded to the cylinder sections along lines 5. Pi receiving sections am then secured in aceas shown by welding on the lines 7. T e whole container is finally annealed and is ready for use. I

The resulting product is made fronra steel 7 fromto 100% higher than thatkjf ordinary low carbon steel and having little inclination to age, and a tank made of this alloy olfers greater safet for several reasons.- ng r" 9f local overeating is minimized because of better heat passage through the thin walls as comlow carbon steel,

en raised to welding temperature either pared to the relatively thick walls required in the use of ordinary boiler plate Also, there is less sensitiveness against overstraining the material either during the period of manufacture or during operation.

Further utility lies in the process of manufacture of containers capable of withstand,- ing hi h temperatures and pressures made from t e molybdenum-aluminum alloy. In-

asmuch as the yield point of this alloy is relatively high at high temperatures, a relatively small allowance for decrease in yield point at these temperatures need be made in I computing the required wall thickness where .the alloy is used, as compared to the liberal allowance that must be made in the case of ordinary low carbon steel. As a consequence, tanks made from the molybdenumaluminum steel can be made of greatly reduced wall thickness as compared to tanks made from the ordinary low carbon steel and it has been found this reduction is so material that the tanks made rom the alloy can be readily welded whereas the high pressure and temperature tanks made from the low carbon steel were necessarily of such great thickness that they couldv not' be readily welded. I

As determined by actual test, vessels of a given strength require but two-thirds of the wall thickness when made of molybdenum steel as compared to vessels made of ordi- 20% in cost of materials, based on present market prices, is effected when the .alloy is used, inaddition'to the great saving in labor incident to the handling and working of the thinner as compared to the thicker plates.

I now claim as new and desire to secure by Letters Patent of the United States is as follows:

1. Molybdenum-aluminum steel having a- .high yield point and little inclination to Having thus described my invention, what aging containing substantially 2% to .5%

molybdenum, and at least 0.5% but less than .1% aluminum.

2. As a product of manufacture, a hollow body adapted for use under high pressure and temperature conditions, said hollow body being made of a steel alloy having a high yieldpoint and little inclination to aging containing as its principal constitu ents, exclusive of iron, substantially .05% to 25% carbon, .2% to .5% molybdenum, and

.05% to 2% aluminum.

3. As a product of manufacture, a vesseladapted for use under high temperature and pressure conditions, the said vessel being 'formed'of welded steel plates having a high yield point and little mclination'to aging containing substantially .0572; to 25% car-' y bon, 2% to .5% molybdenum, and at least .05% but less than .1% aluminum.

4. The method of making a hollow steel. body adapted for use under high tempera- 5 ture andpressure conditions, which consists in making plate having a high yield point and little inclinationto aging containing as its principal constituents, exclusive of iron, substantially .05%- to 25% carbon, 2% to .5% molybdenum and .05% to 12% aluminum, and forming the hollow body from said plate. 5. The method of making a steel vessel adapted for use, under high pressure and 15 temperature conditions which consists in forming plates from steel having a high yield point and little inclination to aging containing a lowpercentage of carbon, 2% to .5% molybdenum and at least .05% but less than .1% aluminum, and welding said plates together to form a vessel.

6. The method of making a steel vessel adapted, for use under high pressure and temperature conditions which consists in forming plates from steel having a high yield point and little inclination to aging containing as its principal constituents, exclusive of iron, .05% to 25% carbon, 2% to .5% molybdenum and .05% to 2% aluminum, heating said plates by the use of water gas, and hammer welding said plates to form a vessel. 7 Molybdenum-aluminum steel having a high yield point and little inclination to aging containing as its princi-palconstituents, exclusive of iron, 2% to .5% molybdenum, .05% to 2% aluminum, and .05% to 25% carbon.

In testimony whereof, we have hereunto set our signatures. FRITZ GORSGHLUETER.

E. POI-IL. 

